diff --git a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/moving/SurvivalFly.java b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/moving/SurvivalFly.java
index a793ed58..368d52d8 100644
--- a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/moving/SurvivalFly.java
+++ b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/moving/SurvivalFly.java
@@ -219,11 +219,11 @@ public class SurvivalFly extends Check {
         }
 
         // Check if head is obstructed.
-        if (!resetFrom || !resetTo) {
-            data.thisMove.headObstructed = (yDistance > 0.0 ? from.isHeadObstructedMax(yDistance) : from.isHeadObstructed()) 
-                    //                    || to.isHeadObstructed() // Best not have this one.
-                    ;
-        }
+        //if (!resetFrom || !resetTo) {
+        data.thisMove.headObstructed = (yDistance > 0.0 ? from.isHeadObstructed(yDistance) : from.isHeadObstructed()) 
+                //                    || to.isHeadObstructed() // Best not have this one.
+                ;
+        //}
 
         //////////////////////
         // Horizontal move.
@@ -2260,7 +2260,7 @@ public class SurvivalFly extends Check {
         final String hBuf = (data.sfHorizontalBuffer < 1.0 ? ((" hbuf=" + StringUtil.fdec3.format(data.sfHorizontalBuffer))) : "");
         final String lostSprint = (data.lostSprintCount > 0 ? (" lostSprint=" + data.lostSprintCount) : "");
         final String hVelUsed = hFreedom > 0 ? " hVelUsed=" + StringUtil.fdec3.format(hFreedom) : "";
-        builder.append("\nonground: " + (data.thisMove.touchedGroundWorkaround ? "(assumeonground) " : "") + (fromOnGround ? "onground -> " : (resetFrom ? "resetcond -> " : "--- -> ")) + (toOnGround ? "onground" : (resetTo ? "resetcond" : "---")) + ", jumpphase: " + data.sfJumpPhase + ", liftoff: " + data.liftOffEnvelope.name() + "(" + data.insideMediumCount + ")");
+        builder.append("\nonground: " + (data.thisMove.headObstructed ? "(head obstr.) " : "") + (data.thisMove.touchedGroundWorkaround ? "(touched ground) " : "") + (fromOnGround ? "onground -> " : (resetFrom ? "resetcond -> " : "--- -> ")) + (toOnGround ? "onground" : (resetTo ? "resetcond" : "---")) + ", jumpphase: " + data.sfJumpPhase + ", liftoff: " + data.liftOffEnvelope.name() + "(" + data.insideMediumCount + ")");
         final String dHDist = (lastMove.toIsValid && Math.abs(lastMove.hDistance - hDistance) > 0.0005) ? ("(" + (hDistance > lastMove.hDistance ? "+" : "") + StringUtil.fdec3.format(hDistance - lastMove.hDistance) + ")") : "";
         builder.append("\n" + " hDist: " + StringUtil.fdec3.format(hDistance) + dHDist + " / " +  StringUtil.fdec3.format(hAllowedDistance) + hBuf + lostSprint + hVelUsed + " , vDist: " + StringUtil.fdec3.format(yDistance) + (!lastMove.toIsValid ? "" : (" (" + (yDistance > lastMove.yDistance ? "+" : "") + StringUtil.fdec3.format(yDistance - lastMove.yDistance) + ")")) + " / " + StringUtil.fdec3.format(vAllowedDistance) + ", sby=" + (data.hasSetBack() ? (data.getSetBackY() + " (" + StringUtil.fdec3.format(to.getY() - data.getSetBackY()) + " / " + data.liftOffEnvelope.getMaxJumpHeight(data.jumpAmplifier) + ")") : "?"));
         if (data.verVelUsed != null) {
diff --git a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/PlayerLocation.java b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/PlayerLocation.java
index 0a01a98a..ae7e18d4 100644
--- a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/PlayerLocation.java
+++ b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/PlayerLocation.java
@@ -701,30 +701,41 @@ public class PlayerLocation {
      * @return
      */
     public boolean isHeadObstructed(double marginAboveEyeHeight) {
+        return isHeadObstructed(marginAboveEyeHeight, true); // TODO: This is changed behavior, need to check calls.
+    }
+
+    /**
+     * Test if something solid/ground-like collides within the given margin
+     * above the eye height of the player.
+     * 
+     * @param marginAboveEyeHeight
+     * @param stepCorrection
+     *            If set to true, a correction method is used for leniency.
+     * @return
+     */
+    public boolean isHeadObstructed(double marginAboveEyeHeight, boolean stepCorrection) {
+        if (stepCorrection) {
+            double ref = maxY + marginAboveEyeHeight;
+            ref = ref - Location.locToBlock(ref) + 0.35;
+            for (double bound = 1.0; bound >= 0.0; bound -= 0.25) {
+                if (ref >= bound) {
+                    // Use this for correction.
+                    marginAboveEyeHeight += bound + 0.35 - ref;
+                    break;
+                }
+            }
+        }
         return BlockProperties.collides(blockCache, minX , maxY, minZ, maxX, maxY + marginAboveEyeHeight, maxZ, BlockProperties.F_GROUND | BlockProperties.F_SOLID);
     }
 
     /**
-     * Test if something solid/ground-like collides within a default margin
-     * above the eye height of the player. Margin is yOnGround + max(0.0, 2.0 -
-     * eyeHeight).
+     * Test if something solid/ground-like collides within a default
+     * margin/estimation above the eye height of the player.
      * 
      * @return
      */
     public boolean isHeadObstructed() {
-        return isHeadObstructed(Math.max(0.0, 2.0 - eyeHeight) + yOnGround);
-    }
-
-    /**
-     * Test if something solid/ground-like collides within the maximum of the
-     * default margin and the given margin above the eye height of the player.
-     * Will add yOnGround to the given margin.
-     * 
-     * @param marginAboveEyeHeight
-     * @return
-     */
-    public boolean isHeadObstructedMax(double marginAboveEyeHeight) {
-        return isHeadObstructed(Math.max(marginAboveEyeHeight, 2.0 - eyeHeight) + yOnGround);
+        return isHeadObstructed(0.0, true);
     }
 
     /**